Epicyclic Clock

Thank you Michael for the link.

I think that Sam was thinking of using the pins fixed to the face of the wheel rather then inside it but as you say, the pinion would not be inside the wheel.

David

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I’m sure he was, David … and equally sure that he will tell me, if am am wrong.

The other geometry, with radial pins [!], would be very difficult to make AND inefficient.

MichaelG.

Edited By Michael Gilligan on 02/11/2022 10:36:24

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using the pins fixed to the face of the wheel

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But presumably the teeth would need to be a different profile 

MichaelG.

Edited By Michael Gilligan on 02/11/2022 10:59:24

I've been stating the obvious again, sorry !

David

Here is a detail of the external meshing, from the svg file

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Someone with superior CAD skills might like to check my assumption that it would lock-up if used with that tooth profile inside the ring.

MichaelG.

I think the use of cycloidal gears for clocks was debunked a long time ago. I've quoted the link in previous posts. For involute gears, the tooth form for internal teeth is the inverse of an external gear with the same number of teeth. If this is a large number, straight teeth might work?

You might enjoy this, Duncan:

**LINK**

https://www.tec-science.com/mechanical-power-transmission/cycloidal-gear/lantern-pinion/

… especially the final two of the graphics

MichaelG.

here's the link . Looks sound to me

Not my usual standard, but you know what I mean David.

With too many unforeseen issues, I'm no longer able to take this much further.

Anyway, who cares if it's cycloidal, involute, convolute, or even inefficient at this stage, you've got to start somewhere. A scrap of plywood and some panel pins comes to mind.

By the way, you're to be congratulated on the progress you've made since we began swapping notes.

I wish you well,

Sam

Thank you Sam. But you know a lot of it is due to the help I've received here from many people not least from you.

Best Wishes, David

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I have just looked at that essay again, Duncan … principally because I realised I had made a contradictory on another thread.

Could you please have a look at this: **LINK**

https://www.tec-science.com/mechanical-power-transmission/involute-gear/meshing-line-action-contact-pitch-circle-law/

Am I right in believing that the centre distance between involute gears is actually quite important ?

… and therefore “The involute tooth prevailed because its motion is independent of center distance variation” might be a false premise ?

MichaelG.

Edited By Michael Gilligan on 05/11/2022 10:54:32

IIRC since there is only one involute curve for a circle of given radius, the effect of varying centre distance of a pair of involute gears is just to vary the effective pressure angle. Nevertheless there are other aspects of tooth design that are important that do depend on pressure angle and pitch circle so it's desirable to use the "right" centre distance.